


A Spartan's Promise

by Sephirron



Category: Supergirl (TV 2015)
Genre: ACO AU, Blood and Violence, Childhood Friends, Crossover, Demigods, F/F, Greek Mythology - Freeform, Kara and Lena grow up in Sparta, Peloponnesian War, Pirates, alternative universe, battle of Thermopylae, greek mythoogy, lost then found
Language: English
Status: In-Progress
Published: 2020-05-22
Updated: 2020-05-22
Packaged: 2021-03-03 01:01:31
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 3,869
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24316216
Author URL: https://archiveofourown.org/users/Sephirron/pseuds/Sephirron
Summary: It's 446 BCE, the Greek world has known peace for some time. Many years passed since King Leonidas I and his army of 300 paid the ultimate sacrifice for their freedom until darkness began to sow in the shadowy depths of Greece's shores. Kara grows up in Sparta, proud daughter to the House of El, aspiring to be a proud warrior like her parents before her. However when her father returns home from a patrol with a young girl, carrying a bloodied broken spear in her fingers - the air smells of war once again.Kara had always wanted to be a true Spartan but as the world changes, long-devised schemes being put in motion, deceit creeping over the horizon, she wonders just how much that will cost her.
Relationships: Kara Danvers/Lena Luthor
Comments: 12
Kudos: 56





	A Spartan's Promise

**Author's Note:**

> Hi o/  
> Welcome to the Supercorp x Assassin's Creed Odyssey AU. Or Greek Mythology AU. Whatever floats your boat (: Events are based on the historical fiction of the game, historical events are not entirely accurate. I see a lot of medieval AUs (bc duh we love Katie McGrath's Merlin moments) and I just thought it'd be cool to see something in a different time period as well - still filled with warriors, monsters, and fantasy. 
> 
> Please enjoy! And no worries if you don't know the storyline of ACO, I try to weave as much background without being too overbearing. 
> 
> (Disclaimer: I own none of the characters from SG or any of the themes from Ubisoft's creations)

Sparta was a proud country and known for its ruthlessness in battle and pride in their own kind. Children, both sons and daughters, were trained from a young age to become warriors and defenders of their home, honor, and family. Some Greek countries viewed this as barbaric – the idea of subjecting children to a life on the battlefield when no war had been fought in decades seemed animalistic in nature and unnecessary.

But if anything, the Greek world sensed a change on its shores. The kind of feeling where doubt licked at their ankles. The quiet hum of aggression and deceit lurked in every shadow. The King of Sparta had fought to protect Greece from the Persian invasion – himself and his army of 300 paid the ultimate price for their freedom. Now, years later, it seemed as though something was stirring within the world and the citizens lived their days with unease – wondering, if ever, they would just turn on one another.

Living in Sparta, Kara didn’t feel this unease. She was proud to be raised as a warrior. Yes, her parents were strict and constantly vigilant of her actions but Kara understood it to be a valuable lesson that would make her stronger. Strong enough to protect her family and those she cared about when they were defenseless.

The lessons were never easy.

“Haaaagh!”

A battle cry was let out as wooden staffs collided with one another in rapid succession. The staff was much too big for Kara at her age but she held her own balance, gripping it between her slightly calloused fingertips. She struck her attacker again, grasping the staff with both hands as she tried to use the range of the staff to her advantage in a stab move. The attacker side-stepped easily and caught the extended staff, yanking it forward, Kara stumbling onto the ground, knocking a bit of dust into the air.

When the dust cleared, Kara blinked at the tip of her opposer’s staff that was angled right before her face. She lost. Again.

The staff withdrew and was struck into the ground with two taps.

“Up, Kara. Again.”

Kara nodded with a small sigh and picked up her fallen weapon. “Yes, Mother.”

Kara’s mother, Alura, was donned in signature Spartan red, her long tunic flowing just past her knees. She stood strong in her ornamental gold leg guards and bracers, her chestnut braid draping softly over her shoulder. She stepped closer and leaned over slightly to Kara’s height.

“A Spartan rises as soon they have fallen.”

Her voice was always soft but there was never room for any doubt that she was right. She was a fighter, a warrior, that could stand alongside any man and woman in battle. Kara knew this well – she would always watch her parents spar at sunrise with rapt attention, her breakfast in a bowl balancing on her knees. They were both fierce, like raging bulls and lions, but she knew that they were enjoying themselves, small smiles always gracing their faces as they vigorously dueled through the sweat. Where Kara’s father excelled in his firm strength, her mother exceeded in grace and precision. Kara only wished she could have that balance within herself or at least another companion.

“Yes, Mother.”

“Ready your staff!”

Kara took a stance and set her jaw, wielding her weapon once again. A moment passed and Kara’s brow twitched, waiting for the slightest movement. Instead, her mother dropped her stance and circled her, observing. Kara felt a sharp poke at her ankles and she reflexively moved away.

“Widen your stance, a soldier grounds themselves. Remember, you want to catch your enemy off balance. You cannot do this if you yourself are not balanced and rooted.”

Kara’s heel twisted and dug into the ground, her muscles tensing, ready to react.

“Good, good. Now approach me!”

Kara lunged forward again, colliding with her mother’s staff in an overhead swing. With a push, Kara jumped back and sprung forward in a launch, not relenting her assault. She went for another stab move and her mother mimicked the same parry as before. As Kara’s body fell forward, she stabbed her staff into the ground and made it her center of gravity as she circled round with a swinging kick that knocked away her mother’s incoming strike from behind. Using this as an opening, Kara pulled her staff from the ground and in another circle motion, made an aim for her mother’s vulnerable side.

The staff was clanged onto her mother’s bracer as she blocked the attack. Kara blinked in surprise, _I almost had her!_

Alura smiled down at her and came to a kneel in front of Kara, discarding her staff to the dirt. A hand came down on Kara’s bare shoulder and squeezed.

“Don’t look so defeated, little one. Had it been a real battle, you would’ve cleaved off my hand!” Alura chuckled.

“I guess… I did better this time, right? I didn’t fall into the dirt like before!” Kara said hopefully, twiddling her fingers on her staff.

“Yes, better. Now come,” Alura huffed, placing their staffs against the side of the stone house. “Your father should be returning soon.”

“Alura.”

Kara and Alura turned at the sound of the voice, greeted at the sight of Jor-El, walking towards them with his helmet held against his side, spear and shield strapped to his back. Kara smiled at the return of her father from his patrols but faltered slightly when he saw that he was not alone. Clutching to the tassels of his leather waist band was a young girl, maybe her age. Her raven hair obscured the pale skin of her cheekbones but Kara didn’t miss the emerald green of her eyes that peeked through. She had never seen anything like it. Kara’s eyes shifted to the bundle of cloth that Lena clenched to her body and if Kara knew any better, there was blood seeping through the ivory.

“Welcome home, my love,” Alura greeted with a brush of her fingertips against Jor-El’s jaw. She turned her attention to his companion, causing the little girl to back away. “And who’s this with you?”

“This,” Jor-El began, kneeling down and putting his hand on the small of the girl’s back, gently coaxing her forward. “Is Lena. She is the daughter of my comrade, Lionel. She’s going to be staying with us.”

Jor-El looked up at his wife and made a side glance towards the front entrance of their home. Alura nodded imperceptibly before offering Lena a smile. She put a hand on her shoulder and also Kara’s, bringing her forward.

“ _Chaire,_ Lena. This is my daughter, Kara.”

“ _Chaire_ ,” Kara smiled brightly, the prospect of a new friend exciting. “It’s nice to meet you.”

“Kara, why don’t you take Lena with you to the fields? There are some herbs that I still need for dinner tonight,” Alura suggested.

“Would that be okay with you Lena? Do you like flowers?” Kara asked, tilting her head. “There are beautiful rows of them next to the herb fields.”

“Okay,” Lena whispered.

Kara bounced on her toes in excitement and dashed inside of the house to collect her things. In a moment’s breath, she was back outside, a leather belt with a pouch slung from her waist, a dagger tucked away into its sheath, and a small circular shield on her back – an adolescent version of her father’s traditional Spartan shield.

“Ready to go?”

“What’s all that for?” Lena asked, eyeing Kara up and down. “I thought we were just getting herbs and flowers.”

“A Spartan is always prepared,” Kara recited proudly.

“I…see,” Lena relented, clutching the cloth a little closer to her chest. “I’m ready.”

Kara turned to her parents. “We’ll be back soon.”

“Do not stray too long, Kara,” Jor-El warned. “Be back before the sun sets.”

Kara nodded and reached for Lena, palm open and inviting. “Come on, Lena. We should get going.”

A blush dusted over Lena’s pale cheeks as she quickly swept her hair over her ear and accepted Kara’s hand. Kara smiled and tugged them along down the dirt path to the fields. Alura and Jor-El watched them go before heading inside. Jor-El began to set his helmet on the table and unfasten the weapons from his back.

“Care to tell me what is happening, my love?”

A long sigh came from Jor-El as he settled his spear and shield against the wall.

“Lionel, Lena’s father, was killed while we were patrolling the northern borders.”

“But the borders of Lakonia and Arkadia are hardly dangerous,” Alura replied skeptically. 

“There was a traitor within our ranks. He ran his spear through Lionel’s back like a coward. He held us off well, surely not the work of a normal soldier. A misthios perhaps.” Jor-El surmised. “I brought him down. Before I ran him through, he spoke through the blood on his face. ‘Death is coming for you Spartan dogs.’”

“You seem shaken by this. This isn’t the first time someone has remarked negatively of our ways,” Alura pointed out.

“Surely, not. But you must have noticed, Alura, the Greek world is changing. War is coming – there are warriors coming from Athens patrolling too close to our borders, like lions waiting to strike down.”

“And what of the girl?”

“I sought Lena out, Lionel had told me stories of his only child. I wished to ease her burden of losing her only family. I gave her Lionel’s spear and she hasn’t let go. I will not leave the child of my comrade alone.”

“She must be trained, Jor-El. If war is coming, Kara and Lena need to be ready for whatever attack at any moment.”

Jor-El hummed in agreement. “She will train with Kara. Kara will protect Lena until she is ready. Of this, I’m sure. I will seek counsel with the Kings at dawn, I must report my findings and my suspicions of these Athenian _dogs._ ”

WWW

Lena sat among the flowers, gently thumbing through the petals as she watched Kara cut at the herbs with her dagger and tucking them away in her pouch. The sun shined down through the clouds and cloaked Lena a blanket of warmth that almost made her feel calm. Kara was kind to her the entire way – she didn’t pry about who she was or where she came from. For that, she was grateful.

Lena became distracted running her fingers over the cloth by her side and plucking a flower from its stem, spinning in between her thumb and forefinger. She jumped slightly when she saw a shadow cast over her and looked up to find Kara grinning down at her.

“May I sit next to you?”

Lena nodded and scooched over, Kara taking her rightful place beside her. Kara began to pick at the ring of flowers around her until there was a pile in her lap. She began to weave the stems together as Lena watched her curiously, admiring the string of various petal colors, from hues of white, lilac, gold, and green. Kara stopped with an accomplished smirk on her face as she presented Lena with the ring of flowers with both hands out.

Lena blinked. “What’s this?”

Kara gave out a hearty laugh and brought her arms up to place the ring on top of Lena’s hair. She fitted it around, straightening her raven locks gently that were displaced by the crown. Kara pulled back and gave a quick once over before nodding in satisfaction.

“It’s a flower crown, silly. You wear it.”

Lena reached up and ran her fingertips softly over the crown, the first smile gracing her face since her life had changed.

“It looks really pretty on you, Lena. The green really brings out your eyes!”

Lena blushed again, casting her eyes down. “Thank you, Kara.”

“Here,” Kara offered her hand which Lena took. “I’ll show you.”

Kara pulled Lena up and guided them down the path. Kara gave Lena’s hand a soft squeeze as they walked side by side. Cautiously, Lena squeezed back. Kara wasn’t sure why Lena was so careful or why her father had said she would be staying with them. But Lena had that far away look in her eyes and she decided maybe it was better not to ask yet.

The pair stopped at the edge of a small pond and Kara crouched down, pointing to the water. Lena peered over the edge and gave a small gasp when she saw her reflection, reaching up once again to the crown again.

“It’s beautiful, Kara,” Lena breathed.

“Of course. I’ll teach you how to make them sometime,” Kara offered.

“Could you teach me how to fight?”

Kara paused, searching Lena’s eyes. She found a soft determination behind the viridian irises and her jaw was set. It was the most direct look Lena had given her since they had met.

“Have you ever held a weapon before?”

At that, Lena began to unwrap the slightly bloodied cloth. Kara watched with anticipation – she had been wondering what Lena had been holding so close all this time. The stained ivory cloth fell away to reveal a spear. Or the remnants of one. The blade was still intact, dried blood running a long its edges but the pole of the spear was snapped, leaving only enough for a hilt. Lena held it by her side and looked back at Kara.

It was quite the sight, to see Lena now standing tall, eyes fiery, flower crown perched perfectly, with a weapon that had seen battle many times in her hands. Her meek exterior was an echo now.

“It was my father’s spear. It was given to me when your father told me he was killed,” Lena explained solemnly.

“How?”

“They told me it was an animal attack. But that can’t be true. My father was a warrior and he would never lose so easily. He always went out hunting and he never had a scratch on him when he came back. It doesn’t make sense.”

“I’m so sorry, Lena,” Kara apologized, taking Lena’s empty hand. “I’ll teach you. My mother and father are good teachers too, they train me every day. It won’t be easy though, they can be very strict.”

“If you stay with me, I’m ready,” Lena affirmed, chewing her bottom lip and intertwining their fingers.

Before Kara could reply, a flock of birds shot upwards like a cloud from the edge of the pond, cawing in warning. Kara turned, putting her arm out in front of Lena protectively. They were greeted by the sight of a tanned wolf, prowling towards the water with its golden eyes striking. Lena fixed her grip, palm sweating against the wooden hilt of her spear. Kara glanced at Lena and put a finger up to her lips.

“Don’t make any sudden movements,” Kara whispered, as she slowly took hold of her own dagger and unfastening her shield from her back. She slipped her forearm through the straps and took a defensive guard with it, keeping her dagger pointed at the wolf, who was drinking from the pond.

“Back away, slowly.”

Lena followed Kara’s lead and backed away, eyes fixated on any movement from the wolf. Kara held her stance as she shifted away, ready to defend them. At that moment, a branch cracked beneath her heel. Kara winced, baring her teeth in frustration and gulping. The wolf’s head snapped up and fell its golden gaze on the pair. It growled loudly and barked, pushing its weight on its hind legs before launching forward towards them.

“Lena, get back!” Kara commanded, digging her heels into the ground. _A soldier grounds themselves._

Kara pushed the wolf back with all her strength, shoving her shield against the wolf’s biting attack. The wolf flung backwards on its hindlegs, shaking its head out of the daze, snarling over its fangs at the duo. The beast sprung again, catching its claws on the top of Kara’s shield, ripping the straps from her forearm, and gouging through her skins.

Kara yelped in pain, blood gushing down to her fingertips as her shield rattled uselessly to the ground.

“Kara!” Lena shouted in horror, watching her protector unable to ignore the pain. Kara’s jaw clenched tightly, nursing her arm close to her body while holding her dagger out, albeit shakily, pointing at the wolf now circling, ready to finish of its prey.

“Lena…” Kara whispered, “You need to run. I’ll hold it off.”

“Kara, no! That beast will kill you,” Lena refused vehemently, voice strained with fear.

“It will kill us _both_ if you don’t get out of here,” Kara protested.

Before the two could argue any further, the wolf charged and Kara rose to its attack while shoving Lena out of the way. Lena stumbled to the ground to watch in shock as the wolf knocked Kara down, pinning her. Kara’s dagger skidded away and she winced, waiting for the beast to finally take her down. She saw the glint of its yellow eyes, triumphant, fangs gleaning and hungry.

“No!”

Kara flinched at the splatter of something wet against her face. She felt no pain and finally opened her eyes when she felt the weight that was once imprisoning her slump off. The wolf laid lifelessly, muzzle bloody from the spear that pierced its head. Kara’s head rolled in Lena’s direction, her hand still outstretched from her throw. Fresh tears were streaming down her porcelain cheeks, hair crazed in wisps, as her floral crown slipped. Kara watched her bottom lip wobble as Lena started to scramble over to her.

Kara weakly rose, using her elbows to sit up just as Lena’s body connected with hers, arms wrapping tightly around her neck, her face burying into Kara’s shoulder.

“You saved me,” Kara remarked breathlessly, raising her uninjured arm to gently wrap around Lena’s waist.

“I couldn’t leave you alone,” Lena mumbled tearily.

Kara sighed in both exhaustion and relief. “Thank you, Lena.”

Lena pulled away slightly and had it not been for her arm scorching from the pain, she probably would’ve laughed at Lena’s petulant expression. Her cheeks were flushed red, jaw set, and viridian eyes shining.

“You have to promise that we don’t leave one another. We’re stronger together.”

“Stronger together,” Kara echoed.

“Honestly Kara, it was a bad decision to try and face that thing on your own,” Lena chided.

Kara blew out a laugh. Lena moments ago was resigned and quiet, unsure of herself. Now, she realized, that she was sorely mistaken.

“What are you laughing at?” Lena asked, narrowing her eyes.

Kara smiled and shook her head. “I was waiting to know what you were really like.

“And what am I really like?” Lena challenged.

In her answer, Kara took her good arm and pulled the broken spear from the wolf’s head, wiping the excess blood on the grass before handing over the weapon, which Lena took gently.

“I can just tell we’re going to be good friends,” Kara said simply.

Lena blinked once before shaking her head in exasperation, then sliding her gaze to Kara’s arm. A frown tugged at her lips at seeing the wound, angry and crimson. She grazed her fingertips on Kara’s wrist, careful to avoid the area, feeling Kara twitch with her nerves firing rapidly to pain, now pulsing.

“We should get you home so your father can look at your wound,” Lena said quietly, underlined with guilt. “It’s probably going to scar.”

Kara got to her feet, holding out her hand to help Lena up. She picked up her dagger and sheathed it. Going for her shield, leather straps frayed, she held it out to Lena.

“The scar is worth it if I protect someone I care about,” Kara offered with a toothy smile.

“You don’t even know me that well, Kara,” Lena pointed out, taking the shield.

“That won’t matter since you’re stuck with me from now on.”

“You should still be more careful,” Lena argued weakly, not correcting Kara on wanting to be with her.

“I’ll always be your friend and I will always protect you. No matter what,” Kara promised.

Lena rolled her eyes good naturedly and breezed past Kara without a word, raven hair obscuring the small smile that was on her lips. Kara soon followed in stride, the pair walking away from the dusk. It went on silently – until Kara’s home came into view. Jor-El had been waiting dutifully on the porch, eyes toward the horizon.

“I promise, too,” Lena vowed into the dimming air. Before Kara could reply, Jor-El had come up to the pair and knelt down, guiding Kara’s wrist closer to his face.

“What happened, Kara? I said before dusk,” Jor-El said, voice stern.

Kara straightened, trying not to wince as her father turned her wrist to look at the full severity of the injury.

“A wolf attacked us and it broke through the straps on my shield,” Kara explained.

“And what of the wolf?”

“Lena saved me. With her spear!” Kara said excitedly, chest puffed with pride for her friend. To prove it, Jor-El caught the bloodied spear in Lena’s grasp.

“You did well to protect one another,” Jor-El approved. “True Spartan warriors will do whatever it takes to survive. So that those they love can also survive.”

Lena and Kara shared a small smile, slight blushes covered by the amber glow of the sun setting.

“Come,” Jor-El stood. “We’ll deliver the herbs to your mother and treat your wounds.”

Both girls followed and as Lena passed through the threshold of Kara’s home she paused, turning her head towards the horizon. She saw the now fading sun as an eagle soared across the sky, piercing the land with its call. She thought about her father for a brief moment. She really had been afraid to be left alone and at first, she didn’t know if she wanted to be a warrior either.

At that point, she wondered if she would ever have a home again.

She felt a gentle hand on her shoulder and looked to find Kara’s concerned cerulean eyes.

“Are you okay?”

_She’s too soft to be like other Spartans,_ Lena thought amused.

She smiled in return and nodded at her friend, fully entering the home, taking a seat beside Kara as Jor-El began preparing to treat Kara’s wound. The air was filled with the aroma of Alura’s cooking and the chatter of Kara retelling the story of the wolf to her father.

Lena gently set her father’s spear against the wall. The hole in her heart was still a great one, but the newfound friendship slowly crept over its edges. She didn’t know what tomorrow would bring, she didn’t know the first thing about fighting.

Kara hissed loudly as Jor-El applied a salve over her wounds then moved to wrap her arm in a cloth bandage. Lena regarded her wound and clenched her slightly bloodied fingers in a fist on her lap.

She would continue to survive, survive so she could protect others, and become a warrior her father could be proud of.

When Kara sent her another smile, now fully bandaged up, Lena smiled back, a bit of happiness finally returning.

**Author's Note:**

> chaire = form of greeting  
> misthios = mercenary
> 
> Idk about you guys but I love Lena/Katie McGrath holding weapons??? Example: Lena blasting that earth bender guy from Leviathan with a laser canon = hot. 
> 
> What do you guys think about Supercorp being in this era? 
> 
> Let me know what you guys think and feedback always welcome! 'til next time!


End file.
